This invention relates to fuel injection control of a diesel engine.
Tokkai Hei 11-36962 published by the Japanese Patent Office in 1999 discloses a diesel engine control device which suppresses smoke generation in a diesel engine. This diesel engine control device controls a fuel injection to keep the excess air ratio lower than 1 at a low engine rotation speed and a low engine load.
When a vehicle is accelerated from a low engine rotation speed by depressing an accelerator pedal, an engine emits more smoke when the engine slowly increases its rotation speed than when the engine quickly increase its rotation speed.
However, in the prior art, the rate of increase of the engine rotation speed is not taken into consideration. Hence, when the vehicle is accelerated from the low rotation speed by depressing the accelerator pedal, the amount of smoke increases if the rate of increase of the engine rotation speed is low.
Therefore, the object of this invention is to control the excess air ratio in response to the rate of increase of the engine rotation speed.
To achieve the above objects, this invention provides a fuel injection control device for use with a diesel engine mounted on a vehicle, the diesel engine comprising a fuel injector that injects fuel into a combustion chamber.
The device comprises a sensor which detects a running state of the vehicle, a sensor which detects a state of increase of an engine rotation speed, and a programmable controller. The programmable controller is programmed to calculate a required amount of fuel injection based on the running state of the vehicle, set an upper limit of an amount of fuel injection based on the state of increase of the engine rotation speed, calculate a corrected amount of fuel injection by limiting the required amount of fuel injection by the upper limit, and control the amount of fuel injection of the fuel injector to the corrected amount of fuel injection.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.